ExxonMobil is by far the least LGBT-friendly company in the Fortune 500. This past December, the Human Rights Campaign issued the company its first-ever negative score on the Corporate Equality Index, which tracks the LGBT inclusiveness of 636 major companies.

Recently, ExxonMobil made another attempt to limit protections for its LGBT employees by blocking shareholders from advancing an equal employment opportunity policy that would protect sexual orientation and gender identity. The company claimed that a “zero-tolerance” policy is already on the books, but the Securities and Exchange Commission did not agree, pointing out that it does not have the same legal force or consistency across the company as the proposed protections:

We are unable to concur in your view that ExxonMobil may exclude the proposal under rule 14a-8(i)(l0). Based on the information you have presented, it appears that ExxonMobil’s policies, practices, and procedures do not compare favorably with the guidelines of the proposal and that ExxonMobil has not, therefore, substantially implemented the proposal. Accordingly, we do not believe that ExxonMobil may omit the proposal from its proxy materials in reliance on rule 14a-8(i)(10).

This could mean that shareholders might finally have the opportunity to advance a modicum of LGBT protections at the company, but the effort by executives to block that proposal is troubling, to say the least. Prior to 1999, Mobil actually did prohibit discrimination based on sexual orientation and offered health benefits to domestic partners of employees, but Exxon removed those policies when the two merged.

ExxonMobil has over 80,000 employees worldwide who could be impacted by the policy. Assuming no further obstructions, the shareholders will vote on the proposal on May 30.